The general hypothesis of the research is: Quantitative 3D measurements of structure an function of the heart can produce more clinically relevant and accurate information than current 2D (tomographic) echocardiographic methods. this hypothesis is to be tested through: 1) Data Acquisition: Our goal is to develop new data acquisition hardware and software for multidimensional ultrasound imaging. The ultimate intent is to produce a generic system for obtaining data from current commercial scanners and probes. The hardware and associated software system will acquire high-quality multidimensional data suitable for investigating quantative 3D methods; 2) Metrological Software and Validation: Programs will be developed to ensure the integrity of the acquired data. These include interpolation of the data from the acquisition geometry of a Cartesian volume, reduction of noise such as speckle or system noise, and separation or segmentation of the desired region from the remainders of the data. We will produce displays that re comprehensible but accurate, including static and dynamic 2D and 3D images. A set of metrological tools will be constructed to make measurements specific to clinical needs; 3) Clinical Measurements: Developed and validated metrologic software will be used to make clinically relevant measurements of multidimensional data. Quantitative 3 D measurements will be compared to conventional 2D data. Qualitative 3D shape and functional will be correlated with clinical information. Focused applications include the atrial septum, mitral valve, ventricles, intracardiac masses, and myocardial involvement by systemic disease. The progress of the first four years of this program has been substantial. We developed new scanning methods and tested them on over 60 patients. Our imaging systems have advanced from producing recognizable but low fidelity volumetric images to high-resolution images nearly equivalent in quality to photos of gross specimens. The importance of these results is that the foundation has been laid on which can be built clinically useful procedures, instruments, and metrological algorithms for analyses of accurate, dynamic 3D computerized "gross" specimens of desired portions of the cardiovascular system in living patients. Certainly the impact of such measurements on cardiovascular research, clinical investigation, and medicine will be significant.